Initially 5.00 mol of helium (which we can treat as an ideal gas) occupies volume 0.120 m3 and is at temperature 20.0C. You allow the helium to expand so that its final volume is 0.360 m3 and its final temperature is also 20.0C. Calculate the net change in entropy of the helium if (a) you make the helium expand isothermally from 0.120 m3 to 0.360 m3 and (b) you first increase the temperature of the helium so that it expands at constant pressure from 0.120 m3 to 0.360 m3, then cool the helium at constant volume to 20.0C.

Initially 5.00 mol of helium (which we can treat as an ideal gas) occupies volume 0.120 m3 and is at temperature 20.0C. You allow the helium to expand so that its final volume is 0.360 m3 and its final temperature is also 20.0C. Calculate the net change in entropy of the helium if (a) you make the helium expand isothermally from 0.120 m3 to 0.360 m3 and (b) you first increase the temperature of the helium so that it expands at constant pressure from 0.120 m3 to 0.360 m3, then cool the helium at constant volume to 20.0C.